The term "growth regulator" is used in its accepted sense in the French language, which corresponds to "growth substance" in Anglo-Saxon literature, the term "growth" relating to the production of living matter and not simply to the modification of the size of plants. Accordingly, growth regulators in the context of the invention are compounds which are capable of modifying the physiology of plants in various different ways.
It has already been proposed (cf. Belgian Pat. No. 782,037) to use methionine and certain of its esters as growth regulators. Unfortunately, compounds of this kind are often not effective enough for commercial application.